Switching system



April 1936- E, E. KLEINSCHMIDT 2,037,472

SWITCHING SYSTEM 1 27 Filed April 16, 1928 3 Sheets-Shae l Z2 g F] INVENTOR I 114115 {fa/041, FWM m 96% a mi.

I/ 22 1/ ,1 TTORXEY.

April 1936- E. E. KLEINSCHMIDT 2,037,472

SWITCHING SYSTEM Filed April 16, 1928 3 Sheets-Sheet 2 INVENTOR d M 205 By 15 W %M a. MIX/ML A TTORNE Y.

A ril ,14, 1936. E. E. KLEINSCHMIDT 2,037,472

SWITCHING SYSTEM Filed April 16, 1928 3 Sheets-Sheet 5 ATTORNEY.

Patented Apr. 14, 19926 UNITED STATES SWITCHING SYSTEM Edward E. Kleinschmidt, Chicago, 1u., assignor to Teletype Corporation, Chicago, Ill., a. corporation of Delaware Application April 16, 1928, Serial No. 270,386

93 Claims.

My invention relates to telegraph systems in which a plurality of signaling lines extending from a plurality of outlying stations terminate at a central station. More particularly the invention relates to automatic switching apparatus for assigning a signaling line extending from a remote station to an idle telegraph set at the central station and for connecting a telegraph set at the central station with any one of the signaling lines for communication thereove'r.

In telegraph systems, the present day practice is to receive all the incoming messages for a large city at a central or main distributing station. This central station is connected to a plurality of scattered sub-stations located in various parts of the'city by radial telegraph lines. The messages received at the central station are re-transmitted therefrom over one of these lines to the particular sub-station located nearest the final destination of the message. Similarly messages which originate at any of these outlying sub-stations are first transmitted to the central station and then re-transmitted to the remote destination. It is evident that in such systems the traflic con- 5 sists wholly of messages between the central station and sub-station without direct communication between any two sub-stations.

In order to properly handle the signaling trafiic a large number of telegraph sets must be located at the central station in preparation to receive messages from or send messages to each of these outlying stations. Inasmuch as it is desirable that any one of these sets may transmit to any one particular outlying sub-station, provision must be made for properly assigning the signaling line connected to the sub-station to any one particular telegraph set. It is equally necessary in the case of messages originating at the sub-station that the signaling line connection to the central station be properly connected to an idle telegraph set at the central station for receiving and re-transn'iitting the message to its remote destination. Heretofore this has been accomplished either by utilizing an independent telegraph set for each outlying station which is expensive, or

by complicated switching apparatus.

Inasmuch as the signaling traflic handled at the central station at peak periods is heavy it is desirable to facilitate quick connections from the central station instruments to any substation and provide simple and reliable supervision of the sub-station line by the central station operator so as to avoid unnecessary attempts to seize busy lines. Since the signaling trafiic varies from a peak load to a comparatively low load, a flexible control of the destination of incoming calls at the central station whereby the total traflic may be concentrated upon a minimum number of operators during hours of low traflic and is distributed or separated into different classes of traffic during hours of heavy traffic.

It is accordingly an object of my invention to provide an automatic switching system in which a minimum amount of apparatus is employed to serve any given number of signaling systems, which facilitates quick automatic connection from a sub-station to a. central station, provides simple and reliable supervision of sub-station lines by the central station operator, provides flexibility in the control of the destination of calls coming to the central station for concentrating the total traflic upon a small number of operators during hours of low traflic and properly distributing the trafiic during hours of heavy trafl'ic; in which complete control of all outlying station telegraph sets is obtained by the central station operator when once a connection is made to an outlying sub-station, in which a. busy identification of all the lines in operation is provided at all times and in which the condition of a remote apparatus is at all times under supervision of the operator.

Further objects of my invention are such as together with the foregoing will appear in the following description of the preferred embodiment of the invention and are such as may be secured by the utilization of the combinations, sub-combinations and principles hereinafter set forth and as defined by the terms of the appended claims.

As shown in the drawings,

Figure 1 is a diagrammatic view of the circuits and apparatus employed in a preferred embodiment of the selecting system at the central station and at an outlying sub-station showing the interconnecting line and the automatic switching apparatus.

Figure 2 is a side elevational view of an embodiment of a preferred form of timing mechanism for rendering the sub-station telegraph apparatus in a non-operating condition at the end of a signaling period.

' Figure 3 is a top plan view of the timing mechanism shown in Figure 2.

Figure 4 is an alternative mechanism for rendering a telegraph set non-operative.

Figures 5 to '7 are diagrammatic views of the alternative circuits and apparatus for locking the telegraph sets at the central station in a nonoperating condition, and

Figure 8 is a diagrammatic embodiment of a preferred arrangement for audibly and visually apprislng an outlying station operator that connections have been completed to his set from the central station.

In Figure 1, a central station A is provided with a plurality of telegraph sets and 2. It will he understood of course that these are merely illustrative and that any number of such apparatus may be located at the central station. In the present illustration certain of the sets at the central station, such as l, are allotted for outgoing messages and the others, such as 2, for incoming messages.

The transmitting apparatus is connected by means of conductors 3 and 4 to automatic switching equipment 5 individual thereto. It will be understood that similar switching equipment is provided for each printing apparatus such as i assigned to outgoing signals although if desired the same automatic switch may be common to a plurality of sets. The automatic switching equipment 5 controls rotary and vertically moving wipers 6 and I which move over a bank of contacts 8 and 9 respectively in a manner to be described in detail hereinafter for connecting the set I through conductors H to any one of a plurality of signaling lines such as l2 connected to telegraph apparatus l3 at the outlying station E. The automatic switching equipment here diagrammatically shown is of the well known type disclosed in Aitkens Automatic Telephony. Conductor I2 individual to outlying station B is also connected by means of conductor I4 to switching equipment l5 which in a manner to be described in detail hereinafter when operated from the outlying station B will connect the signaling line l2 extending to the outlying station irom conductor I4 to any idle receiving telegraph set 2. A bank of lamps I6 comprising lamps individual to each signaling line iii are connected with both automatic switching apparatus 5 and i5 and indicate at all times which of the lines ex tending to the remote or outlying sub-stations are busy. The operators at the central station by observing the lamps avoid useless effort in attempting to connect to a busy line.

The telegraph apparatus I comprises a printer magnet is and transmitter IQ of the well known type such as described in the patents to Krum '#1,595,472 issued August 10, 1926 and to Kleinschmidt #1567392 issued December 29, 1925. A lamp 2!! is connected in series with this telegraph set for indicating to the operator by its flashing when communication is being carried on by this set with some outlying station. The current for such signaling is provided by battery 2| connected to ground at 22. A busy alarm 23 is connected in multiple with magnet l8 and operates in a manner to be described for apprising the operator that the line he has picked is busy. Device 23 is connected through condenser 24 to round so that direct currents are kept out and y alternating currents to which device 23 esponds pass through. A motor 26 connected o battery 27 is connected over conductor 28 to witch. til controlled by key 3|. The motor 26, t will be understood in operation controls the printing apparatus in accordance with the operaof the magnet it responsive to signaling impulses. Normally motor 26, magnet l8, and transmitter it are connected to each other through a contact 32 and inasmuch as batteries Bi and ill are connected in opposing relations, no current flows and the apparatus is in a nonoperating condition. The key 3| which is oil the snap-operating type has three positions, a mid closed in preparation for signaling operations,

motor 26 is started into rotation. Simultaneously magnet I8 is energized and since the magnet is energized during a normal non-operating or stop period, no operation occurs at this time although the motor 26 is rotating. A similar circuit for the motor 26 is controlled over switch 34 when the key 3| is in its upper position.

With key 3| in its lower position, set is connected for outgoing messages only. With key 3| in its upper position, the set operates for incoming messages. Switches 34 to 36 complete circuits for the set i from automatic switches i5 to condition the set for incoming signals, in the manner to be described in detail hereinafter. A relay 4| which is normally energized controls the final connection of the main signaling circuit to the telegraph set over armature 42. Relay 4| is normally energized and connects the main conductor 4 to trip magnet 43 which energizes in response to the first impulse received to open switch 44 controlling the circuit of relay 4|. Switch 44 is also controlled by a timing mechanism 45 to be described in detail hereinafter for reclosing the circuit of relay 4| an interval after signaling has ceased.

A dial 46 connected in line 4 is also provided at the central station individual to each set to enable the operator thereat to transmit a predetermined code to the automatic switch 5 to seize a predetermined signaling line extending to an outlying station. Dial 46 is of the usual type employed in automatic telephony. Its shunt switch 41 temporarily maintains a circuit closed to the local telegraph set while the dial opens and closes line 4 for signaling.

In telephone practice the opening and closing of a line for transmitting the signals to operate the automatic switching apparatus removes current from the telephone receiver and transmitter. In telephone operation, this is endured. When, however, as in the case of telegraphy, it is desired to maintain the printing apparatus in a normally closed circuit during non-operating periods, provision must be made for maintaining the apparatus closed during the signaling period inasmuch as an open signal is a start operation for the apparatus which is accordingly started in the event that the printer circuit is opened while the automatic switching operations are taking place. This is clearly undesirable. In the present case such operations are avoided by the contact 41 on the dial 46 to maintain the circuit to the telegraph apparatus closed. A switch 48 connected in pilotconductor 3 varies the resistance in this line as it opens and closes for varying the luminosity of a lamp connected therein whereby the operator is apprised of the signaling line to which he is connected. Switch 49 opens this circuit for restoring the apparatus to normal. These operations will be described in detail hereinafter.

As described above, the automatic switching apparatus 5 is connected to the telegraph set over conductors 2 and 4. Automatic switching apparatus 5 comprises a bank of contacts 8 and 9 over which the wipers 5 and I move in a vertical and rotary motion under control of the vertical stepping magnet 5| and rotary magnet 52 respectively. This apparatus is of well known construction in the telephone art as described in Aitken referred to above and is here illustrated diagrammatically. An ofi normal switch 53 is arranged to maintain its contacts 54 and 55 normally disengaged and contact 56 is engaged while the switch wipers 5 and I are in their normal non-operating position. Upon the first energization of the vertical stepping magnet 5|, contact 56 opens and contacts 54 and 55 close.

Receiving relay 51 is connected in the line circuit and responds to impulses from the dial 46 for operating the vertical and rotary stepping and no circuit can be completed for magnet 55.

A slow to operate relay 65 is energized in response to the first impulse received at switch 5 and switches these impulses to the vertical stepping magnet 5| over armature 56. At the end of the first group of impulses relay 55 de-energizes to switch the signal to rotary stepping magnet 52. In the event that the line which is selected is busy, this relay will remain energized thereafter and will connect the alternating current generator 68 to the line 4 at armature 69 for operating the busy alarm device 23 at apparatus I. If the line seized by the automatic switching apparatus is idle, relay 51 de-energizes to prepare a circuit for relay I5 at armature I5. Relay I5 energizes when the line seized is idle and completes the switching operation at armature 11. At armature 18 the pilot circuit 3 is switched to pilot line 19, individual to line I2 and outlying sub-station B. At armature 8| the circuit for restoring magnet 64 is opened preventing energization of this magnet during signaling operations andat armature 82 the circuits for rotary magnet 52 and slow release relay 5'! are opened. As will now be clear the switching apparatus 5 operates for outgoing signals to select the particular line extending to the outlying station B with which the signaling is desired, I

. A different form of connector switch I5 is employed to operate in response to incoming signals for connecting an outlying station to an idle local set. Receiving relay 9| is normally energized and connected over its armature 92 and its front contact and the back contact and armature 93 to conductor I4 connected through resistance 94 to signaling line I2, extending to the outlying station B individual to automatic switch I5. As will be described hereinafter, relay 9| operates in response to the first operation at station E for connecting slow to operate relay 95 in circuit with the line I4. Thereafter this relay operates to energize the stepping magnet 95 over armature 91. Stepping magnet 96 controls the wipers 98 to I00 of switches IOI to I03 respectively. Each of these switches comprise in addition to their individual wipers, a set of bank contacts about which the wipers successively engage in a manner which is well understood in the telephone art and is described in detail in Aitken referred to above. Relay I04 controlled over armature I 05 connects the local set to the signaling line over armature 93, connects thepilot circuit to the set at armature I55, and prepares a restoring circuit at armature I!" as will be described in detail hereinafter.

Switch IllI controls the restoring circuits, switch I02 tests the sets to determine whether they are busy, and switch I03 completes an energizing circuit to the set selected, as will be described hereinafter.

One such set 2 is illustrated in Figure 1. As in the case of set I it comprises a receiving magnet III and transmitter II2 connected in series with a lamp H3 and battery II4. This set is controlled by a motor- 5 connected in circuit with battery H5. The telegraph set and motor are normally in non-operating condition, their batteries being connected in opposition at armature contact I". Relay H8 controlling contact II I is energized over a circuit including switch I I9 controlled by timing mechanism I20 similar to mechanism 45. Normally the line I2I is con-- nected over armature I22 to trip magnet I23 controlling switch H9. When relay II8 de-energizes this circuit is switched to include magnet III and transmitter II2. At armature I23 the pilot line I24 is connected to switches I25 and I25. Switch I25varies the resistance in the pilot line to whichhe is connmted and switch I25 opens this circuit to restore the apparatus to normal as will be described in detail hereinafter.

The extension of pilot line I24 is connected to a lamp I27 Individual to the line I2 extending to circuit to apprise the operator of' the outgoing 7' outlying station B. The illumination of this lamp I21 provides a continual indication of the lines which are busy. 1 I

While the signaling trafllc is heavy, it is desirable that independent telegraph sets be employed for the outgoing signals and for the incoming signals. When, however, the traflic becomes light. it is preferable to operate the same sets for both classes of signaling. This is accomplished' by switch member III controlling switches I32 to I34. In the position shown in the drawings, the telegraph equipment2 is connected to respond to incoming signals. When, however. the load becomes comparatively light and it becomes more desirable to switch the incoming signals to telegraphapparatus I, switches I32 to I34 are moved to their lowermost position.

At the remote station substantially similar apparatus is employed. The signaling line I2 is normally connected over armature I to the release magnet I42. The magnet I42 controls a I switch I43 through which the energizing circuit for relay I44 is completed. At its armature I45, relay I44 controls the energizing circuit for the motor I45 and at its armature I4I controls the net I48 and the transmitter I49 of telegraph set I50. A key I5I is connected in series with this circuit to enable control of the circuit by the operator. The apparatus and its operation will now be more clear from the detailed descriptions of the operations which occur when the operator at the central station wishes to communicate with any one of the outlying stations and when an operator at an outlying station desires to com municate with the central station. It will be first assumed that the operator at telegraph set i desires to communicate with the outlying station B.

Normally the motor I46 at the outlying station is in non-operating condition inasmuch as its circuit is open at armature I45 due to the energization of relay I44 over a circuit including the switch I43. Although an energizing circuit is at this time completed for the magnet I42 from ground through the key I53, the winding of the magnet I42 armature I4! and its front contact over conductor I2, resistance 94, conductor I4, armature 93 and its back contact, armature 92 and its front contact, and through the winding of relay BI to battery and ground, the energy transmitted over this circuit from the battery, because of the arbitrarily high resistance of the winding of relay 9| is insufficient to operate the magnet B42 and accordingly the switch I43 remains in the position shown. The receiving magnet I48 and the transmitter 649 are therefore normallydisconnected from the signaling line at armature Mil.

At the central station trip magnet 43 is normally open circuited at the switch 29 which isin its open position while the switch arm 3| is in its neutral non-operative or mid-position. Relay 4! is energized over a circuit including the switch 44 in its closed position and prepares a circuit for the trip magnet 43 over its armature 42 and its front contact. The motor 26 is at this time open circuited at the switches 42 and, 33 which are in open position and similarly the receiving printer magnet 48 and transmitter I9 are open at the same contacts.

In order to start operations, the operator at set i will move his switch arm 3i to the position shown in Figure 1. A circuit is thereupon completed from ground over switch 33, motor 26 and battery 21 to ground. Motor 26 starts rotating and prepares the printer set for operation. Simultaneously an energizing circuit is completed for the magnet I8 from ground through battery 2I, pilot lamp 211, transmitter contact I9, magnet I 8, make before break contact 32, resistance I6! and ground over. the switch 33. Inasmuch as energization of magnet I8 is the stop condition of the printer set, it will now remainin its non-operating condition with the motor 26 rotating.

A circuit is also completed for the trip magnet 43 from ground through battery, winding of the trip magnet 43, front contact and armature 42, over the conductor E62, switch 29 and its lower contact, through the contact of the code transmitter 46, conductor 4, armature I7 and its back contact, conductor I63 and through the winding of the automatic switch operating relay 5! to ground. This impulse from the battery transmits sufficlent current to operate the trip magnet 13 and relay 5?.

Energization of the trip magnet 43 operates the switch 46 to open the circuit of the relay 4|. Relay 4i upon deenergization opens the circuit of trip magnet '43 at armature 42 which has now moved to engage its back contact and as a result the circuit of the magnet I8 and transmitter I9 is switched from the switch 33 to conductor I62, switch 29 and the signaling line 4. Inasmuch as this circuit is closed through relay 5! the magnet stood by those skilled in the art.

I8 remains energized during this switching operation. It will be noted that this circuit is completed by the make before break armature 42 before the original circuit for magnet I8 is opened so that no break in the circuit of this magnet occurs.

At the automatic apparatus 5, the relay 51 energizes as a result of the circuit traced above therethrough to operate its armature 59 into engagement with its front contact and as a result an obvious energizing circuit is completed for the slow to operate relay 58. The energization of the slow to operate relay 58 prepares an energizing circuit at armature 62 and its front contact, off normal switch 56 over conductor I64, winding of the slow to operate relay 65 through the vertical stepping magnet 5| and battery to ground. The operator will now operate his dial 46 to transmit a predetermined combination of impulses to the automatic switch 5.

As the impulses are transmitted, the relay 5'! of the automatic switch 5 deenergizes and reenergizcs. Upon the first deenergization of the relay 5I, the energizing circuit for the vertical stepping magnet 5I is completed over the armature 59 and its back contact and armature 62 and its front contact and over the circuit traced above through the relay 65 and magnet 5I in series to battery and ground.

Relay 65 energizes and prepares a locking circuit for itself at armature 66 and vertical stepping magnet 5| is energized thus mechanically stepping wipers 6 and I to their first operating level. Althcugh the circuit for relay 58 is opened at this time, it remains energized because of its slow to deenergize characteristic and relay 5'! is again energized by the succeeding impulse before relay 58 can deenergize.

Upon energization of relay 51, in response to the next impulse, the vertical magnet 5I deenergizes. It will be understood by those skilled in the art that each contact on the switch banks such as contact I65 is connected to the individual line extending to an outlying station such as B, and similarly a contact such as I66 is connected over pilot conductor 79 to an individual lampsuch as I21.

This first operation of the automatic switch closes contacts 54 and 55 of the off normal switch and opens contact 56 in a manner well under- Opening of contact 56 opens the original circuit for slow release of relay 65 but its locking circuit is now extended through unnumbered contact in the offnormal switch and front contact and armature 62. When now the relay 5! is deenergized at the end of this impulse, relay 65 is locked over the back contact and armature 59 and vertical stepping magnet is energized a second time.

It will be assumed that in the present case the operator transmits three impulses to step the wipers 6 and 1 vertically to the third level in this case shown uppermost. Thereafter a pause occurs while the dial 46 is being reset during whichthe relay 5'! remains energized. During the transmission of these impulses in closing the circuit of the vertical stepping magnet 5I the slow to operate relay 65 remained energized over a circuit in series with the vertical stepping magnet, front contact and armature 66, the now closed off normal switch contact unnumbered, front contact and armature 62 and the back contact and armature 59 to ground following each deenergization of the relay 51. The intervals when relay 57 is energized are too short to pernit relay 66 tov deenergize. Atihis time, however, the line is maintained closed while the dial 46' is being reset and the relay remains energized for a suiiicient period to permit the slow to operate relay 66 to deenergize and armature 66 moves to engage its back contact. The original energizing circuit for the slow to operate relay 65 is now opened at t! normal contact closed contact unnumbered of the of! normal switch 53, armature 66 and its back contact, and armature 62 and its back contact, through the winding. of the. rotary stepping magnet 62 to battery and ground. The rotary magnet 62' as it is now energized and deenergized with each deenergization and reenergization of the relay 51 will move the wipers 6 and 1 in a rotarydirection to the first and then to thesucceeding contacts. In the present case it will be assumed that two such impulses are transmitted and the switch wiper 1 ultimately rests on'the contact I66 and the switch wiper 6 rests on the contact I66. In multiple with the rotary stepping magnet 62, an energizing circuitis also completed for the relay'61 from ground through battery, the lower winding of the relay 61, back contact and armature 62 over the armature 66 switch contact unnumbered and armatures 62 and 59 to ground.

Upon the first energization of the relay 61, a circuit is prepared for the busyringer generator 66 at armature 69- and its front contact. At armature 16, a locking circuit is prepared for the relay 61, through its upper winding armature 16 and the wiper 6. At the end or the-second' group of impulses, a pause again occurs of suiilcient length to. permit the slow relay 61 to deenergize while relay 51 is held energized causing its armatures 16 and 69 to move to their back position. At this time. thejswitch wiper 6 is in engagement with its contact I66. Should the selected line be idle the circuit irom battery through relay 61 to wiper 6 meets a circuit from battery through lamp I21 to contact I66 and wiper 6 and also a circuit from battery'through the driving magnet 96, contact I16, relay I66 and wires I26 and 19 to contact I66'and wiper 6 and current will not flow. The slow relay 61' therefor deenergizes and a circuit is now completed for the upper winding of relay 16 from groundthrough the upper winding 01' relay 15, back contact and-armature 1.61 over the brush 6 in engagement with contact I66, conductor 19, and dividing through the pilot lamp I21 tobattery and ground, and also through wire I26, re-

lay I04, and magnet 96 to battery and ground. As a result oi this circuit relay 15 is energized and the. lamp I21 is illuminated indicating to the operator at set I that he has seized the line with which the lamp I21 is associated insuring correct connection. .A locking circuit is now completed'tor the relay 16 through its lower winding, from ground through battery the lower winding of the relay 16, front contact and armature 6| over the pilotv conductor 3 and through the contacts of the switches 19 and 66 to ground. The operation of the armature 8| not only locks the relay 15 in its energized position but also opens the circuit for the releasing relay 66 at the back contact, opens a iurther point in the circuits for the slow to operate relay 61 and the rotary stepping magnet." at armature 62 and opens the circuit of the relay 61 at armature 11. At the make or break-contact oi armature 16 the pilot line 6 is connected .over wiper 6 and contact I66 directly to lamp I21 over conductor 19. The armature '11 transfers the circuit for the signaling line] from relay 51 controlling the automatic s'witcl i' 6, tothe signaling line II extending to the outlying station.

-In the event t tithe signaling line II which is engaged by tha -6 and 1 is busy, that is connected to some other set at the central station with which communication is being carried on, the conductor is in a manner to be described in detail hereinafter, and when seized by automatic switch I, an energizing circuit is completed. The relay 61 therefore remainsenergized aiterthe brush 6 engages the contact I66. This circuit is completed from ground through battery, upper winding of the relay 61 front contact and armature 16, make beiore break contact of the relay 16,-at armature18 brush 6 in engagement with the{contact I66, conductor 19 to ground as willbe described. The relay 61 when thus maintained energized, maintains the energizing circuit for the relay 16 open at armature 16 to prevent this relay from energizing and at armature "closes the circuit ior'the generator 66 over armature-.69 and itsiront contact, conductor 6' through switch 29], conductor I62 armature 42 in engasementwith its backcontact, and through'the busy aiar'm 263to ground. -'The dispatcher is then apprised by this alarm signal that connection has beenv'made with a busyline and will therefore, restore his apparatus until the line becomes idle for It will be noted that ac t'in multiple with the lamp I21 is completed for the winding of relay I66 from ground on conductor 19 as traced above over conductor I26 through the winding of relay I66, and thewinding oixthe stepping magnet 96 in a de-energized condition to battery and ground. Themagnet 96 is not energized over this circuit as the current from the battery is insuiiicient to operate it. Relay I66 is however, energized andoperates its armaturestobreak their back contacts. The armatures of relay I 64 and 96 have a mechanical connection so that it relay 96 is not.

energized armature I66 and 93 cannot engage their front contacts, although armature I61 can and maintains relay 9| energized. It will be noted that as the contact of dial 6 opens the line circuit '6, a switch 41 completes an energizing circuit for the magnet I6 from ground through the switch It will be assumed that the line I2 has seized, that the relay 61 has completed an energizing circuit for relay 16 which thereupon locks itself. A circuit isnow completed from the telegraph set at the central stationto the telegraph apparatus at the remote station, the circuit being completed from ground through battery 2 I', lamp 2!! transmitter I9, magnet I 6, make'before break contact in engagement with the armature 62, con- Meier M, switch 29 in its lowest position, conwhich he is connected. Transmitter I9 .is now i tact and armature I4I the winding of the release magnet I42 and through the key I53 to ground.

Magnet I42 is energized over this circuit and operates the switch I43 to open the energizingcircuit for the relayI44. The de-energization of the relay I44 completes an obvious energizing circuit for the motor I46 at armature I and its back contact. At armature I a make before break circuit is completed connecting the telegraph magnet I48 and transmitter I49 in circuit with the conductor I2 and in series with the magnet I8 and transmitter I9 at the central station. The telegraph transmitter and receiver at the central and remote station are nowconnected in series, the magnets being energized for a stop condition. Lamp i2! is at this time illuminated over a circuit 'traced aboveto indicate the line seized. Since however, a number of lines may be busy, it is desirableforthe operator to check the particular line with which he is connected. This is accomplished by operating key 48 to change the resistance in the pilot circuit including the lamp I21. I If this lamp is dimmed by this operation the dispatcher will thus be apprised of the line with operated in accordance with the code to be transmitted and the magnet I48 at the outlying station B operates .in response to this code to control the printer thereat. It will be observed that during this period, the operator at the central station has full control of the signaling line at switch 49 and may continue communication with the outlying station as long as desired.

When communication isno longer desired the operator at the-central station by operating his key 49 opens the circuit of conductor 3 whereupon the locking circuit for the relay 15 traced above is opened and this relay deenergizes. Upon the deenergization of relay 15, an energizing circuit is completed for the restoring magnet 64 from ground through battery, the winding of the restoring magnet 64, closed contact 54 of the oil normal switch 53, armature 63 and its back contact, back contact and armature 8|, conductor 3 and through switches 49 and-48 to. ground. Re-

storing relay 64 when energized, functions to return the wipers 6 and 1 to their normal non-' operative condition. An interval of time after signaling ceases, timing mechanism operate switches 44 and I43 to restore their respective sets to non-operating positions shown.

In the event that the operator at the outlying station B desires to communicate with the central station, the apparatus being in normal nonoperating condition. he will operatebriefiy the key I53, opening briefly the energizing circuit of the relay I42 at the outlying station and the relay 9| at the central station. Deenergization of the relay 9I releases its armature92 which closes a circuit for the relay 95 from ground and battery through the winding of the relay 95, back contact and armature 92, back contact and armature 93, wire I 4, resistance 94, wire I2, front contact and armature Ml, winding of magnet,

I42 and key I53 to ground. Owing to the arbitrarily high resistance of the winding of relay 95, the current in this circuit is insufficient to operate the magnet I42, but the relay responds. Energization of relay 95 of the automatic switch I5at the central station completes an energizing circuit'for the stepping magnet 96 from ground through battery to the winding of the stepping magnet 96 its own back contact, armature 91, and its front contact, back contact and armature I 06 and through the brush wiper 99 to ground. At armature I05, the conductor I26, isnow grounded.

. nections short-circuit the relay I04 which therefore remains deenergized at this time. The current flow in magnet 96- being however, directly grounded at wiper 99 as traced above this stepping magnet is energized to operate its pawl for stepping the switches from their normal contact to their'second contact and at the same time, opens its own energizing circuit at its contact I10. The stepping magnet 96 is thereupon deenergized to again close its circuit over the circuit traced above, except that at this time the brush'99 being in engagement with its second contact, the circuit extends over conductor I24 switch I33 in its upper position, to armature I23 and its back contact, if the relay H9 is deenergized and ground over switches I25 and I26. In the present case, the relay 8 being energized, this indicates that the apparatus 2 is in a non-operating condition, that is, that it is in condition to be seized by'the operator at the remote station. Since the circuit for this stepping magnet 96 is opened at armature I23 the only circuitthrough stepping magnet 96 is com pleted from ground through battery through the winding of the stepping magnet 96, its back contact I10, winding of the relay I 04 and armature I05 and its front contact, to ground. The current flow is insufficient to operate the stepping magnet 96 but sumcient to energize the relay I04. Upon energization of the relay I 04 a circuit is tion to the central station from ground-through key I53, trip magnet I42, armature I4I, line wire .vertive control of the called station, and the calling station has remained non-operative until a time subsequent to its connection to the called station.

The deenergization of the' relay I44 also permits the armature I4I to connect the line I2 through the printer-magnet I48, the sender I49 and the switch I5I to ground, and to disconnect thetrip magnet I42 from the line I2. Simultaneously the deenergization of the relay II8 permits the armature I22 to connect the wire I2I through the printer-magnet III, the sender II2, the lamp II 3 and the battery II4 to earth, and to disconnect the trip magnet I23 from the wire I2l.

The energization of the relay I04 has operated completed from the apparatus at the remote staits three armatures I01, 93 and I06. The operation of the armature 93 has caused the operation of the trip magnets I42 and I23 as described. The operation of the armature I 01 reenergizes the relay 9I over an obvious circuit, thus operating its armature 92 and opening the circuit of the winding of relay 95 which in turn will release its armature I05 to open the circuit over. which the relay I 04 was energized, but the armature I05 of the relay 95 is slow-to-release and before .it breaks its contact the relay II8 will have'provided a holding circuit for the relay I04, as follows: From earth and battery through magnet 99, contact I10, winding and front contact and armature I06 of relay I04, brush 99, wire I24, switch I 33, armature I23, switch I25 and switch I26 to ground. This circuit maintains the connection thus set up and the connection may be released only by the manual operation of the key I29.

The simultaneous operation of the relays I 44 and H9 has completed the circuit between the telegraph set at the central station and the telegraph set at the remote station, from ground through battery II4, lamp II 3, transmittercontact II2, magnet III back contact and armature I22, switch I34, conductor I2I, second contact and wiper I00, front contact and armature 93, conductor I4, resistance 94, conductor I2, make before break contact I, magnet I49, transmitter contact I49 and switch I5I to ground. Signaling communication may now be carried on between these two stations.

If the switches upon engagement with their second contact complete a circuit to a telegraph set such as 2 which is in operative condition at the time; that is, is busy communicating with I some other station, relay I I9 would be deenergized whereupon a circuit is completed from the earth of key I26 over conductor I24, second contact and wiper 'I02, armature I06 and its back contact, front contact and armature 91, to the stepping magnet 99, and battery. Relay I04 would not be energized as ground on conductor I24 shunts the winding of relay I94. Magnet 99- is thereupon againenergized to step the wipers to the succeeding contact connected to the next telegraph set. In this manner the wip-; ers 99 continue to operate from contact to contact until switch contacts are reached at which the apparatus is not in operated condition in which case stepping magnet 99 and relay I04 receive current in series whereupon the latter operates and connects the signaling line I4 through ,to the particular set with which the switch wipers are connected.

Upon energization of the relay I04, it will be observed that a multiple circuit is completed from ground on conductor I24 over armature I09 and its front contact, conductor I26, to the lamp I21 and battery-to ground, apprising the operator at the central station that the signaling line to The wiper I pauses briefly upon the busysignal contact point'to prolong the signal upon the device "I.

The means for stopping briefly is the vacant point unnumbered on switch I02. As shown, in

normal condition the wiper 99 is in connection with earth. When the search starts, relay 95 is charged, relay I04 is uncharged. Busy wires I24,. keep wiper 99 connected to earth when all printer lines are busy, until wiper 99 reaches its last point before normal; on this point there is no 10 wire I 24, no earth, no busy test, no shunt for relay I04 and relay I04 operates, stops the switches I02 (99) and I03 (I00) and sends current for the audible-signal device "I at station B. Relay I04 has opened the circuit of relay 95 and during the delay of the slow-to-release relay 95 the audible-signal condition continues. Reiay 95 now releases armature I05, closing circuit for operating the magnet 96 through armature 91 and brush 99 to earth at I01, and the switches I02, I03 pass to normal position, interrupting the audible signal.

It will be .observed that even in the case of incoming s gnals, the operator at the central station retains complete control of the signaling operations and may signal for extra information. In order to be assured of the particular out- .lying station with which he is in communication he needs only to operate his switch I25 which will cause the lamp I21 to dim and brighten as the switch is operated apprising him thus of the particular line with which he is connected. As soon as the operator at the central station is through communicating he will operate his switch I26 opening the locking circuit for the 36 relay I04 traced above. Relay I 04 thereupon deenergizes and at armature 93 connects the line I4 through to the relay 9|. An energizing circuit is now completed for stepping magnet 96 from ground through battery, winding of the stepping 40 magnet 99 and its own contact I10, armature 91 and its back contact. wiper 99 and the contact with which it is in engagement over the back contact and armature I01 to ground. Stepping magnet 99 steps the wipers 99 to I00 to their succeeding contact, and opens its own circuit and upon deenergization again completes its own circuit. This operation continues until the wipers are restored totheir normal position shown.

A further result of the operation of armature 93 to its back contact is to open the energizing circuit for the telegraph apparatus at the central station. The timing mechanism I20 and I41 operate after an interval of time to close thecircuits of relays H9 and I44 respectively which in turn open the energizing circuits of the motor I49 and connect magnets I29 and I42 in preparation for operating switches H9 and I43.

In the above description of the apparatus it will be observed that the telegraph apparatus at I operates for outgoing signals and telegraph apparatus 2 operates in accordance with incoming signals. During part 01 the operating period however, the traflic becomes so light that it can all be carried by just one set of apparatus. In such a case the switch I3I is operated, and switches I33-I34 are moved from their upper to their lower positions. Switch I33 transfers the connect'ons oi pilot conductor I24 from the apparatus at 2 to the apparatus at I over conductor I12 while the switch I34 transfers the circuit over conductor I2I from set 2 to set I over conductor I13. Set I is then in condition to both send out the signals and receive incoming signals,

Switch I32 moving from its contact opens the circuit for the motor II rendering the telegraph set 2 in a non-operating condition.

A mechanical form of time release is shown in Figures 2 and 3. A time gear I88 is driven through worm gear I8I mounted on and rotatable be utilized. The motor I83 through meshing gears I95 and I98 and clutch I98 drives the cam I91 which at every revolution engages the follower I84 and lifts the follower I84 from the worm I85. The printer clutch I98 engages only while printing operations are taking place. As soon as the printing ceases, the clutch disengages and the follower I84 is permitted to be operated by the worm I to engage the contact I81. It will be understood that contact I81 is the equivalent of contacts II9, I43 and 44 in Figure 1. When the trip magnet I98 is energized, the armature I9I rocks upon its pivot and engages the follower-frame I92 thus rocking the frame I82 about its pivot I83 against the tension of the spring I94.- The rocking of the frame I92 lifts the worm-follower I84 free from the worm I85 thus permitting the spring I88 to move the follower I84 to release the contacts I81 to permit the contacts to open. The trip magnet I98 of Figure 2 appears iii-Figure 1 at 43, I23 and I42.

In order to apprise the station. 13 operator that signals are being received, a special code bar 28I Figure 8, is operated by the first code transmitted from the central station to the outlying station selected. Upon the operation of the bar 28I, in the manner described in the above referred to patent, the pivoted operating lever 282 is rocked about its pivot 283, as the bar 28I engages the horizontal pin 284 extending from lever 282. Lever 282 is rocked and operates the visual indicator 285 through a slot 286 in the frame 281 as shown in the dotted lines. This gives a visual indication to the operator at the outlying station that connection has been completed for communication from the central station. The operator thereafter restores the visual indicator 285 to its position. Simultaneously the hammer 288 is released at the latch 288' and as the cam 289 rotates the hammer 288 operates against the bell 2 I8 to give an audible indication to the operator. Upon the complete rotation of the cam 289 the hammer 288 is again operated to its latched positlon shown.

In Figures 4-7 modified arrangements are disclosed. As shown in Fig. 5 relay 2I5 of the slow to operate type maintains its armature 2 I6 in en-.

gaged position with its contact during the period while the signaling line such as line I2 Figure l is closed through telegraph apparatus at the outlying station. The telegraph current is of sufiicient intensity to maintain armature 218 in engagement with its point contact which in turn closes an energizing circuit for the relay 2". Relay 2 I1 upon energization closes an energizing circuit for the motor 2I8 at armature 2I9 and its front contact and the motor and telegraph set will accordingly be in operation while telegraph signals are being received. The relay 2I5 however, is marginal in character and when communication ceases and the line closes for the supervisory currents only, it is of insumcient intensity to maintain the armature 2Ii in engagement with its contact, and armature 2I6 after energizes and armature 2I6 drops to its back con- I tact, opening the circuit of the relay 2I1 which in turn opens the energizing circuit of the motor 2I8. A bypass circuit is completed around the transmitter contact 22I at armature 228 so that apparatus including the magnet 222 is rendered non-operative thereafter. The switch 223 corresponding to I53 in Fig. 1 is rendered non-opera- ,tive during the signaling period. The busy signal device 224 as usual is connected through condenser 225 to ground at 226.

Figure 4 shows an alternative equipment for station 13 of Figure 1. The line I2 becomes 243. The busy signal I1I becomes 245 and 246. The printer and sender I48 and I 48 become 234 and 244. The motor I46 becomes 221.

A motor-stopping pull-bar 228 is arranged to engage a pivoted bar 228 and also to close a switch 238. The motor-starting magnet 232 has an armature 242 which is at the same time a latch for the bar 229.. The bar 229 operates a set of contacts 23I, 233, 235. The motor starting magnet 232 is connected to earth through the starting key or calling key, and it has the guard relay 231 of low resistance ascompared with magnet 232. The relay 231 is normally free from ground connection but it may be connected to ground through the switch 238 or through its own armature contact.

The apparatus is shown in its non-operating condition. The bar 229 is latched by the armature 242. The line wire 243 is connected through the contact 233 and through'the magnet 232 and the calling key to ground. The printer 234 and sender 244 are open-circuit.- The motor is opencircuit. The relay 231 is open-circuit. The supervisory current through the central ofllce relay 9I is flowing through the magnet 232 but is I insumcient to operate the magnet.

In operation, should the switch 5 connect with the line 243, current of signaling value will flow through the magnet 232 and will energize the magnet to operate its armature 242 to release the pivoted bar 229. This will reverse the contacts 23I, 233 and 235. The contact 23I will energize the motor 221. The contact 235 will close, forming a, path from the line wire 243 through the contact 235, printer magnet 234 and sender 244 to ground. The contact 233 will open, removing the line wire 243 from the magnet 232 and from the relay 231. Normal telegraphic signaling conditions thus are set up.

Should the operator at the apparatus of Figure 4 desire to call the central office to send a message, the starting key is operated briefly. This releases the supervisory relay 9I of Figure 1 and when the switch I5 of Figure 1 has connected the set 2 of Figure 1 to the line I2 which is the line 243, the action at Figure 4 will be the same as described above in response to switch 5.

When signaling is completed, the central office must release the line 243 but before doing so the operator at the central sends to the printer magnet 234 the predetermined code combination oi signaling conditions which will control the printer to operate the motor-stopping pull-bar 228. The bar 22s operates, closes the switch 238, rocks the bar 229, reverses the contacts 23!, 233, 235 and brings the bar 229 under the latch 242. The line 243 is removed from the printer magnet 234 and is connected through magnet 232 to earth, shunted by the relay 231 and switch 238 to earth.

' Relay 23] operates and closes its path through its own armature to earth. Magnet 232 does not control its armature because its winding is shunted by the comparatively low resistance of the relay 231, This condition continues as long as the full signal current continues. When the central office operator releases the line l2 and the current in the line is reduced to its supervisory intensity, the relay 231 will release its armature and the apparatus will be again in its non-operating condition as at first described.

As shown in Figure 1 the apparatus at the central station may also be restored to normal autornatically in an interval of time. Details for restoring manually rather than automatically are illustrated in Figures 6 and 7. In Figure 6 the code transmitter and switching mechanism, mo-

tor and code transmitter receiver are all similar to that shown in Figure 1 and are accordingly labelled the same. The signaling line however, extending from the switch 29 is here shown con- .nected to a key mechanism 260 comprising switches ASE-264, a locking armature 265 and magnet 266. Normally the magnet 266 is connected to the line over the switch 26l in engagement with its contact. When switch v29 closes its contacts, atelegraph current is impressed across the line which energizes the magnet 266 to operate armature 265 releasing the switches controlled thereby. Switch 26l operates a make before break contact and signaling line is switched thereover from the magnet 266 to the printing apparatus receiver relay l8 and transmitter I9, and the test circuit is closed at switch 263. At the end of the signaling period thekey 261 is operated by the central station operator to restore switches to the position shown, permitting the latch 265 to'drop and engage them and hold them in their latched position.

In Figure '7 this automatic equipment is shown in connection with the telegraph equipment for receiving incoming signals. The equipment is identical with that shown in Figure 1 and the same figures are therefore employed. Switch I34 is shown connected through the switch 210 to relay tilt and thence to battery 212 and ground. The current flowing over conductor I 2| is normally insufficient to operate relay 2'. When a telegraph signal is received however, relay 2' energizes and moves its latch armature 273 to release the contacts of the switches 210, 214, and 275 and the signaling line 12! is switched from a connection with relay 2' to the receiving apparatus over the switch 215. At the end of the sig naling period the switch 216 is operated and will restore the switches to the position shown.

It will be clear that following a selection of a substation, a start impulse may be transmitted from the central station which will start the apparatus at the outlying station into operation. A code for spacing impulses will then be received from the outlying station by means of which the phase and synchronisms of the two sets can be compared by the central station operator.

Although I have shown my invention as applied to a preferred embodiment, it will be clear that it may be practiced in many other forms and I do not intend to limit myself to the arrangements 1. In a telegraph system, a central station, a remote station, a. telegraph set at said remote station comprising a telegraphtransmitter and receiver magnet, a motor for operating said telegraph set, means for maintaining said motor normally in a non-operating condition, a telegraph set at said central station, automatic apparatus, and means at said remote station for operating said automatic apparatus to condition said remote and said central station set for intercommunication, said first mentioned means being controlled from said central station for starting said motor into operation and for simultaneously rendering said second mentioned means non-operative, said first mentioned means being also operative when said motor is in a non-operating condition for rendering said transmitter non-operative.

2. In a signaling system, a first station, remote stations, a plurality of'signaling lines at said first station extending to said remote sta-' tions,-a bank of lamps comprising a lamp individual to each of said signaling lines, automatic switching means for seizing one of said lines, the lamp individual to,said line being automatically illuminated when said line is seized and means for varying the luminosity of said lamp to indicate which of said lines is seized.

3. In a telegraph switching system, a first station, a plurality of remote stations, signaling lines extending to each of said remote stations, a. lamp at said first station individual to each of said lines, automatic switching means for seizing one of said lines, said lamps being illuminated as their associated lines are seized whereby a plurality of said lamps may be illuminated at any one time and means operative following the seizing of any one of said lines for varying the'luminosity of the lamp individual thereto whereby indication is provided of the line seized.

4. In a telegraph switching equipment, a first station, a plurality of remote stations, signaling lines extending from said first station to said remote stations, a lamp individual to each of said tor being energized while said receiver is stopped in a normally non-operating condition, automatic switching equipment, a signaling line connecting said set to said automatic switching equipment, a dial in said signaling line, means for operating said dial to open and close said line for transmitting codes of impulses to said automatic switching equipment, means for maintaining said receiver unoperated while said line is being opened by said dial.

6. In a telegraph system, a telegraph set comprising a transmitter and a receiver magnet, an automatic switching equipment, a signaling line connecting said switching equipment and said set, a dial in said signaling line, said telegraph receiver magnet being normally energized during a.

stop or non-operating period, means for operatarmature of said receiver magnet non-responsive to said signals.

7. In a telegraph system, a first station, a plurality of remote stations, signaling lines extending from said central station to each of said remote stations, automatic switching equipment, a plurality of receiver sets at said central station comprising transmitters and receiver magnets, a

telegraph set at each of said remote stations each comprising a telegraph transmitter and receiver, means at said central station for operating said automatic switching equipment to seize one of said signaling lines, means responsive thereto for Starting said transmitter and receiver at said remote station individual to said seized line into operation, means for maintaining the receiver magnet at said remote station energized following the starting of said receiver motor individual thereto into operation, means for maintaining the receiver magnet at said central station energized while said switching operations occur and means for connecting said telegraph sets in series with each other while retaining the printers unoperated.

8. In a telegraph system a central station comprising a first group of telegraph sets arranged for outgoing signals, a second group of telegraph sets for incoming signals, a plurality of outlying stations, signaling lines individual thereto, automatic switching equipment individual to said first group of sets for connecting said sets to any one of said signaling lines extending to said outlying stations and a second automatic switching equipment individual to each of said outlying stations controlled therefrom for automatically connecting the line from said outlying station to any one of said incoming sets.

9. In a telegraph system, a plurality of outlying stations, lines individual to each station, a central station, comprising a first group of telegraph sets arranged for outgoing signals, a second group of telegraph sets for incoming signals, automatic switching equipment individual to said first group of sets for connecting said sets to any one of said signaling lines extending to said outlying stations, a second automatic switching equipment individual to each of said outlying stations controlled therefrom for automatically connecting the line from said outlying stations to any one of said incoming sets, and means operative for conditioning one of said sets for either outgoing or incoming messages.

10. In a telegraph system a central station comprising a plurality of groups of telegraph sets, a plurality of outlying stations, signaling lines individual to each of said outlying stations, automatic switching equipment connecting one group of said sets to said signaling lines, said automatic switching equipment being responsive to control from a central station, additional automatic switching equipment individual to each of said outlying stations and controlled therefrom for connecting said signaling lines from said outlyingstations to any one of said other groups of said telegraph sets and means for connecting said one group of said sets to said additional automatic telegraph switching equipment.

131. In a telegraph system, a central station, a plurality of outlying stations, signaling lines connecting said central station with each of said outlying stations, means for automatically connecting said central station with each of said outlying stations, audible and visual signaling devices at each of said outlying stations, telegraph sets at each of said outlying stations normally in non-operating condition, means at said central station for rendering said sets operative and for operating said audible and visual signaling devices, and means at said outlying stations operative an interval of time after signaling between stations has ceased for automatically rendering said telegraph sets thereat non-operative.

12. In a telegraph system, a central station comprising a plurality of telegraph sets, a plurality of outlying stations comprising telegraph sets, motors individual to each of said sets at said outlying stations and normally in a nonoperating condition, means at each of said telegraph sets at said central station for starting the motor at any one of said outlying stations into operation, means for communicating with said one outlying station, and means at said outlying station operative after an interval of time for rendering said motor thereat non-operative.

13. In a telegraph system, a station comprising a plurality of telegraph sets, a plurality of re-. mote outlying stations each having a telegraph set, signaling lines connecting each of. said outlying stations with said central station, automatic equipment controlled from said centralstation for connecting any one of said central station sets with an outlying station, automatic switching equipment controlled from said outlying station for connecting said outlying station with said central station sets, and means at said central station operative following any one of said connections whereby all signaling is controlled from said central station and is discontinued solely under control from said central station.

14. In a telegraph system, a station comprising a plurality of telegraph sets, a plurality of remote outlying stations each having a telegraph set, signaling lines connecting each of said outlying stations with said central station, automatic equipment controlled from said central station for connecting any one of said central station sets with an outlying station, automatic equipment controlled from said outlying stations for'connecting said outlying stations with said central station sets, means at said central station operative following connections whereby all signaling is controlled from said central station and is discontinued solely under control of said non-operating condition and means at said central station for rendering said set operative and for operating said audible and visual signaling devices.

16. In a telegraph system, a calling station, a called station, switching means under control of said calling station for effecting connection with said called station, means solely controlled by said called station for releasing the connection thus established, and means including said switching means for transmitting code combinations of marking and spacing conditions between said calling and called station.

17. In a signaling system, a calling station, a called station, switching means controlled by said calling station for effecting connection with said called station, means whereby said called station following said connections maintain sole control of said connection, and means including said switching means for transmitting code combinations of marking and spacing conditions between said calling. and called station.

18. In a signaling system, a calling station, a plurality of called stations, means controlled by said calling station for selectively effecting connection with one of said called stations, means .whereby said called station following said connection retains sole control of said connection, and means including said switching means for transmitting code combinations of marking and spacing conditions between said calling and called station.

19. In a telegraph system, a central station, a plurality of remote outlying stations each having a telegraph set, a signaling line connecting each of said outlying stations with said central station, automatic equipment controlled from said central station for connecting said central station with one of said outlying stations, automatic 1 switching equipment controlled from said outlying stations for connecting said outlying stations with said central station and means at said central station operative following .any one of said connections whereby said connection is solely under control from said central station.

20. In a telegraph system, a central station, a plurality of remote outlying stations, each having a telegraph set, a signaling line connecting each of said outlying stations with said central station, means controlled from any one of said outlying stations for connecting said outlying" station with said central station and means at said central station following said connections whereby said connection is under sole control and means. at said central station following said connections whereby said connection is under sole control from said central station.

22. In a telegraph'system, a central station, an outlying station, a signaling line connecting said outlying station with said central station, automatic equipment controlled from said central station for connecting said station with said outlying station, automatic switching equipment controlled from said outlying station for connecting said outlying station with said central station and means at said central station operative followingany one of said connections whereby said connection is maintained solely under control from I said central station.

23. In a telegraph system, a central station, an outlying station, a signaling line connecting said stations, automatic switching equipment controlled from said outlying station for connecting said outlying station with said central station and means at said central station operative following said connection whereby said connection is maintained solely under control from said central station.

24. In a telegraph system, a plurality of outlying stations, a central station, a signaling line connecting said central station with each of said outlying stations, a plurality of telegraph receiving apparatus at said central station, means whereby the first idle one of saidcentral station's receiving apparatus is seized in response toan operation from said outlyingstations therewith and means whereby the release of the seized apparatus is solely under control from said central station.

25. In a telegraph system, a central station having a plurality of printing apparatus thereat, a plurality of outlying stations, a signaling line extending from said central station to each of said outlying stations, automatic switching equipment at said central station, means controlled from said central station for operating said auto-,

matic switching equipment, means responsive to said automatic switching equipment for seizing one of said outgoing lines and means responsive to an operation at one of said outlying stations for connecting one of said central station apparatus to said outlying station signaling.

26. In a signaling system, a central station, a plurality of outlying stations, a plurality of apparatus units at said central station, a signaling line extending from said central station to each of said outlying stations and means whereby any one of said central station apparatusunits may be connected with an outgoing line to one of said outlying stations, either under control from said central station or from said outlying stations.

27. In a signaling system, a central station, a plurality of outlying stations, a plurality of apparatus units at said central station, a signaling line extending from said central station to each of said outlying stations and means whereby any one of said central station apparatus units may be connected with an outgoing line to one of said outlying stations, either under control from said central station or from said outlying stations and means whereby following said connection saidconnection is maintained solely under control from said central station. I 28. In a telegraph system, a first station, a re- Imote station, a telegraph set comprising a trans-- mitter and a telegraph receiver, automatic switching equipment, a signaling line connecting said set to said automatic switching equipment,-

a dial in said signaling line, said telegraph apparat'us being normally disconnected from said signaling line, means to operate said dial to transmit code impulses over said line to operate said automatic switching equipment, and means operative following the complete operation of said switching equipment to complete connections to said outlying stations for associating said printing apparatus with said signaling line.

29. In an automatic telegraph system, a central station, a plurality of apparatus thereat, an outlying station, a single signaling line connecting said stations, automatic switching equipment under control from said central station for seizing said signaling line and switching equipment at said central station responsive to an operation from said outlying station over said signaling line for associating one of said central station apparatus with said signaling line.

30. In a signaling system, a central station, a plurality of outlying stations, a signaling line extending from said central to each of said stations, and automatic means whereby connections from said central to one of said outlying stations associated with one of said signaling lines may be effected from either end automatically.

3].. In a signaling system, a central station, a plurality of outlying stations, a signaling line extending from said central to each of said stations, an automatic means whereby connections from said central to one of said outlying stations associated with one of said signaling lines may be effected from either end automatically, and means whereby following said connection, it is maintained solely under control from said central station.

32. In a signaling system, a central station, a plurality of apparatus thereat, a plurality of outlying stations, a signaling line extending from said central to each of said outlying stations, automatic Switching equipment, means controlled from said central station for operating said auto-' matic switching equipment to seize one of said signaling lines for connecting the central station apparatus with the apparatus at said outlying stations associated with said signaling line, and switching means at said central station responsive to an operation from an outlying station over the signaling line associated therewith for connecting one of said central station apparatus with the signaling apparatus at said outlying station over said signaling line.

33. In a signaling system, a central station, a plurality of apparatus thereat, a plurality of outlying stations, a single signaling line extending from said central to each of said outlying stations, automatic switching equipment, means controlled from said central station for operating said automatic switching equipment to seize one of said signaling lines for connecting the central station apparatus with the apparatus at said outlying stations associated with said signaling line, and switching means at said central station responsive to an operation from an outlying station over the signaling line associated therewith for connecting one of said central station apparatus with the signaling apparatus at said outlying station over said signaling line, and means whereby following said first-mentioned connection, said first-mentioned connection is maintained solely under control from said central station.

34. In a signaling system, a central station, having a plurality of apparatus, a plurality of outlying stations each having apparatus, a signaling line individual to each of said outlying stations extending from said central station to its individual outlying station, switching equipment at said central station, means controlled from said central station to operate said switching equipment to associate one of said apparatus thereat with a predetermined one of said signaling lines, means responsive to their association for associating the apparatus unit at the outlying station with said signaling line, a second switching equipment at said central station, means controlled from any one of said outlying stations for operating said second switching equipment and means responsive to the operation of said second switching equipment for associating one of said central station apparatus with said signaling line and simultaneously associating said outlying station apparatus with said signaling line.

35. In a signaling system, a central station, having a plurality of apparatus, a plurality of outlying stations, having apparatus, a single signaling line individual to each of said outlying stations extending from said central station to its individual outlying station, switching equipment at said central station, means controlled from said central station to operate said switchequipment to associate one of said apparatus 'zh L mi ed one of said signaling lines, the last mentioned. means for associating the apparatus at the outlying station with said signaling line, a second switching equipment at said central station, means controlled from said ou ying station for operating said second switching equipment, means responsive to the operation of said second switching equipment for associating one of said central station apparatus with said signaling line and simultaneously associating said outlying station apparatus with said signaling line and means whereby following said connections said conneo-- tions are maintained solely under control from said central station.

36. In a signaling system, a central station; a local circuit thereat; printing apparatus normal- 1y connected in said local circuit, an outlying station; a signaling line connecting said stations, printing apparatus at said outlying station normally disconnected from said signaling line, automatic switching equipment, means controlled from said central station for operating said automatic switching equipment, means responsive to said automatic switching equipment operation for seizing said outlying station, and means responsive to the seizing of said outlying station for connecting the printing apparatus thereat to said signaling line and for disconnecting the apparatus at said central station from its local circuit and connecting it to said signaling line.

37. In a telegraph system, a central station, an outlying station, a local circuit at said central station, a signaling line connecting said stations, telegraph apparatus at each of said stations, said telegraph apparatus at said central station being normally connected in said local circuit, switching mechanism, means controlled by either of said stations for operating said switching mechanism for connecting said central station with said outlying station, and means operative following said connection for disconnecting said telegraph apparatus at said central station from said local circuit and for connecting said telegraph apparatus at said central and said outlying station to said signaling line.

38. In a telegraph system a central station, an outlying station, a closed local circuit at said central station, a signaling line connecting said stations, telegraph apparatus at each of said stations, said telegraph apparatus at said central station being normally connected in said local circuit, switching mechanism, means controlled by either of said stations for operating said switching mechanism for connecting said central station with said outlying station, and means operative following said connection for disconnecting said telegraph apparatus said central station from said local circuit and for connecting said telegraph apparatus at each of said stations to said signaling line, said central station telegraph apparatus being normally in closed circuit condition and maintained in the same condition while switched from the said local circuit to said signaling line.

39. In a telegraph system, a central station, an outlying station, a local circuit at said central station, a signaling line connecting said stations, telegraph apparatus at each of said stations, said central station telegraph apparatus being normally connected in said local circuit thereat; switching mechanism, means controlled by either of said stations for operating said switching mechanism for connecting said central station with said outlying station, means operative following said connection for disconnecting said an outlying station, a local circuit at said central telegraph apparatus at said central station from said local circuit and for connecting said telegraph apparatus at each of said stations to said signaling line, said central station telegraph apparatus being maintained in the same condition as obtained when connected in the local circuit while being switched to said signaling line.

40. In a telegraph system, a central station,

station, a signaling line connecting said stations, telegraph apparatus at each of said stations, said central station telegraph apparatus being norcentral station telegraph apparatus in the same condition as obtained when it is connected in said local circuit during switching.

41. In a telegraph system, a central station having a plurality of telegraph apparatus, a plurality of outlying stations, a plurality of signaling lines connecting said stations, switching equipment, means controlled from said central station for operating said switching equipment to connect one of said signaling lines with one of said central station apparatus for communication with one of said outlying stations, second switching equipment, and means controlled from any one of said outlying stations for associating any one of said central station apparatus with the signaling line to said outlying station for permitting communication therebetween.

42. In a telegraph system, a central station, a remote station, a line circuit connecting said stations, a motor at said remote station, a receiver and a transmitter at said remote station, said transmitter being operable to send telegraphic signals by opening said line circuit in code manner, switching apparatus at said central station connected to said line circuit and responsive to a brief opening of'said line circuit, and means for starting and stopping said motor, said means being operative to render said transmitter incapable of opening said line circuit when in condition to stop said motor.

43. In a telegraph system, a central station, a remote station, a line circuit connecting said stations, a motor at said remote station, a receiver and a transmitter at said remote station, switching apparatus at said central station connected to said line circuit and responsive to a brief opening of said line circuit, a calling key at said remote station adapted to open said line briefly to control said automatic apparatus, and means for starting and stopping said motor, said means being operative to render said calling key ineffective when in condition to energize said motor to run.

44. In a signaling system, a plurality of signaling lines, busy indicators, one for each of said lines, means to engage a line for signaling and for displaying the indicatorthereof; and further means for controlling the indicator variably;

45. In a signaling system, a plurality of signaling lines, a busy indicator for each of said lines, a pilot conductor connected to said busy indicator over which said busy indicator is operated, automatic switches to engage a line for signaling and for operating said indicator, and means to vary the operation of said indicator by varying the current in said pilot conductor.

46. In a signaling system, a signaling line, a pilot conductor for said line, a busy-guard connection for said conductor, an indicator for said conductor operated by said connection, and

means for operating said indicator variably while maintaining said busy-guard connection continuously effective.

47. In a signaling system, an automatic switch, a telegraph set, a source of current, a closed circuit including said switch, said set and said source and having a continuous current through said set and through said switch, and means for interrupting the current through said switch while maintaining the current continuously through said set.

48. In a signaling system, an automatic switch, a telegraph set, a source of current, a closed circuit including said switch, said set and said source and having a continuous current through said set and through said switch, a first dial-operated switch which deprives said automatic switch of current in a variable code manner, and a second dial-operated switch which provides current for said set in a continuous manner.

49. Ina signaling system, an automatic switch, a telegraph set, a source of current, a closed circuit including said switch, said set and said source and having a continuous current through said set and through said switch, and a dial-operated mechanism adapted to operate said switch independently of said set.

50. In a telegraph switching system, a telegraph set, a local circuit for said set, line cirsuits for said set, switches for transferring said from its local circuit to a line circuit, and makebefore-break-contacts for maintaining said set unoperated during the transition from circuit to circuit.

52. In a signaling system, a central station, a plurality of sub-stations, a single circuit connecting a substation to the central station, a concentration system located at the central station comprising a plurality of recorders, a message distribution system located at the central station comprising a plurality of transmitters, means at each central station transmitter to control said distribution system, and means at each substation to control said concentration system; both of said systems being operable over said circuit.

53. In a signaling system, a first station, an outlying station, signaling apparatus at each station, selector mechanism at said first station, and means whereby said selector mechanism at said first station may be variably controlled from either of said stations for effecting a connection between the signaling apparatus at said stations.

54. In a signaling system, a message relay station, a plurality of remote stations, a plurality of outgoing signaling sets at said relay station, a plurality of storing signaling sets at said relay station, signaling apparatus at each of said reat one of said remote stations for transmission of a message stored on one of said storing signaling sets, and means whereby said switching mechanism may be controlled from. any one of said remote stations for effecting a connection be- I tween the apparatus of said remote station and one of said storing signaling sets at said relay station.

55. In a signaling system, a'relay station, a plurality of outlying stations, a plurality of message storlng and transmitting sets at said relay I station, signaling apparatus at' each of said out- V lying stations, switching mechanism at said relay station associated with said message storing sets, other switching mechanism at said relay station associated with said transmitting sets,

means whereby said transmitting switching apparatus may be controlled from said relay station for efiecting a connection between one of said transmitting sets and the apparatus at any one of said outlying stations for transmission of a message stored on one of said storing sets, and means whereby said storing switching apparatus may be controlled from any of said outlying stations for effecting a connection between the apparatus thereat and one of said storing sets at said relay station.

56. In a signaling system, a first station, a plurality of outlying stations, a plurality of incoming and outgoing signaling sets at said first station, signaling apparatus at each of said outlying stations, switching mechanism at said first station associated with said outgoing sets, other switching mechanism at said first station associated with said incoming sets, means whereby said outgoing switching apparatus may be controlled from said first station for effecting a. con nection between one of said outgoing signaling sets and one of said outlying stations, means whereby said incoming switching apparatus at said first station may be controlled from any of said outlyingstations for efiecting a connection between said apparatus thereat and one of said incoming signaling sets at said first station, and a single signaling line in which the apparatus at each of said outlying stationsis connected.

57; In a signaling system, a central a plurality of outlying stations, a plurality oi coming and outgoing signaling sets at said central station, signaling apparatus at of said outlying stations, switching mechanism at central station associated with said cute sets, other switching mechanism at said central station associated with said incoming sets, means whereby said outgoing switching apparatus may be controlled from said central station for ef= fecting a connection between one of said outgoing signaling sets and one of said outlying stations, means whereby said incoming switching apparatus at said central station may be conceiving message storing and transmitting signaling sets at said central station, signaling apparatus at each of said outlying stations, switch transmitting switching apparatus may be controlled at said central station to effect a connection between one of said transmitting sets and one of said outlying stations, for transmission of a message stored on one of said receiving sets,

means whereby said receiving switching apparatus at said central stationmay be controlled from any of said outlying stations for effecting a connection to one of said receiving sets at said central station, a single signaling line' connecting each of said remote stations to said central station, means whereby all of said operations between the outlying stations and said central station are effected over said single signaling circuits, and asignaling device at said central.

station individual to each of said signaling lines for indicating a busy condition of said lines.

59. In a, signaling system, a relay station, a

plurality of outlying stations, a plurality of intion associated with said incoming sets, means whereby said outgoing switching apparatus may be controlled from said relay station for effecting a connection between one of said outgoing signaling sets and one of said outlying stations, means whereby said incoming switching apparatus at said relay station may be controlled from any 01 said outlying stations for effecting a connection between the apparatus thereat and one of said incoming signaling sets at said relay station, a single signalingline connecting each of said outlying stations to said relay station, means whereby all of said operations between said relay station and said outlying stations are effected over said single signaling circuit, means including said single signaling circuits for communicating between signaling apparatus and sets connected thereto, a signaling device at said relay station individual to each of said signaling lines for in-- dicating a busy condition of said lines, and means whereby said signaling devices may be variably operated from said relay station incoming and outgoing signaling sets for indicating to an attendant, the line to which the relay station apparatus is connected.

60. In a signaling system, a relay station, a plurality'of outlying stations, a plurality of incoming and outgoing signaling sets at said relay station, a signaling set at each of said outlying stations, switching mechanism at said relay station associated with said outgoing sets, other switching mechanism at said relay station associated with said incoming sets, means whereby said outgoing switching apparatus may be controlled from said relay station for efiecting a connection between one of said outgoing sig naling sets and one of said outlying stations, means whereby said incoming switching apparatus at said relay station may be controlled from any of said outlying stations for effecting a connection between the set thereat and one of said incoming signaling sets at said relay i station, a normally non-operating motor for each of said outlying signaling sets, and means responsive to a connection between any of said signaling sets for starting the associated nonoperating motors into operation.

61.In a signaling system, a relay station, "a

pluralityof outlying stations, a plurality of in-" coming and outgoing'signaling sets at said relay station, a signaling setat each jof said outlying of 'theconnection;

stations, switching mechanism at said relay station associated with said outgoing sets, other switching mechanismi'at said relay station associatedwith said incoming sets, means where coming" vsignaling]sets at'said relay station, a

normally non-"operating mot r for each of 7 said' outlying lsign'aling sets,* means responsive 'to a connection eflected between anyof said signaling sets for starting'the associatednomoperating motors intooperatiom'andme'ahs whereby an attendant at said relay stationretains full'control of the signaling circuit rollowing the inter connection or any pair of said sets through said switching 'mechanismfirrespective to! the origin 62. In asignaling system, a central station, a

plurality f outlying stations, 1 a plurality or in-" coming and outgolng'signalingsets at said central station, asignalingset at each of said outlying stations, switching mechanism at said central, station associated said dutgoingsets, other switching mechanism'at 'said'central sta-- tion associated with said" incoming* sets, means whereby ,said outgoing "switching apparatus may be controlled irom said central station for effecting. a connection between one of said outgoing signaling sets and theISet' at one of saidfoutlying stations, means whereby 'sai'df incoming swltchlngapparatus at'jsaid relay station may becontrolled from any of said outlying stations for eflecting a connectionbetween' theset there at and, (men! said incoming signaling sets at said central station, fa normally" non-operating motor for each of said outlying sets, means responsive to a connection effected between any pair of said sets for starting the associated nonoperating motors into operat'ion," means whereby an operator at said central station retains full control of the signaling circuit followin the interconnection-of any pair oi said sets through said switching mechanism irrespective of the ori-' gin of, theconnection, and means for transmittinga special calling signal from said central station to' a connected outlying station.

63. In a signaling system, a concentration station, a plurality of substations, telegraph apparatus and a. ,motor at each substation, a searching switch at the concentration station, a plurality of printing telegraph apparatus connected to the searchin'gjswitch, means at a substation for starting the searching switch into operation, and means operated when .the search ing switch has seized a receiver to start the motorat the substation. I I 7 64.111 a signaling system, a concentration station, a plurality of substations, a searching switch at the concentration station, a plurality of printing telegraph apparatus connected to the searching switch, means at a substation to start the searching switch into operation to seize one of said apparatusand means operated when a telegraph apparatus has been seized to indicate at the sub'stationvthat the apparatus has been seized. 65. Ina. signalingsystem, a calling station, .a

non-operating motor at saidcalling-station, a' called station, circuit controlling apparatus at a point intermediatejof said calling and called stations, and circuits and relays'for starting said motor, said circuits being controlled from said calledstation through s'aid apparatus to said calling station.

tral oflice, a searching switch, acalling station served by said switch, a plurality of service circuits' which said' switch' engages "in succession,

a further circuit engaged by said switch after' said switch has engaged successively said serv-' ice circuits, said'further circuit containing an audible signal "device at said calling station and asource of power atsaid central office', and

means for stopping said switch briefly in engage ment with said'further circuit and for then restoring said switch to normal.

67. Ina signaling system, a first station; a

7 second" station, a normally closed line circuit connecting said flrstjstationand said second station, a normally energizedrelay in said line circuit at saidflrst station, means in said line circuit at said second station for opening said 1 line circuit to de-energizesaid relay, means including contact points fof s'aid relay 'for' eliminating 'said'relay from said line-circuit when said relay de-energizesfa'nd motor mechanism renderedpperative by'said relay while said resecond station, a'line wire, a normally closed line, circuit connecting said first station and said second station, a normally energized relayin said line circuit at said first'station,"means in said line circuit at "saidsecond station'for'opening said line circuit to de-energize said relay, 8- motor mechanism at said 'first station, means ineluding contact points of said relay for eliminating said relay from said'fline circuit when said relay de-energizes, and further means including further contact points of said relay for con'ditioning said motor"mechanism"to operate while said relay remains deenergized. v

69. In a telegraph system, telegraph sets each' having a lamp associated therewith, another telegraph set having a key associated therewith,

.said lamps being grouped adjacent to said key,

and switching means to connect one of said sets to said other set andto connect the associated lamp to the associated key whereby said connect ved key may control said connected lamp to identity said connected one of said sets.-

70. In a telegraph system, a first station, a plurality of second stations, signaling lines connecting said first station with each of said sec- 0nd stations, a plurality of telegraph receivers at said first station, means tor originating calls at said second stations, and means at said first stations to a central receiving station, transmitting apparatus atv said outlying stations for initiating calls, a plurality of telegraph receivers at said central receiving station arranged in a predetermined sequence, and means for invari- 10' -66. In anautomatic switching system, a cen- I ably assigning incoming calls to the lowest num bered idle receiver.

72. Ina telegraph system including lines ex tending from a plurality of outlying stations to a central receiving station, transmitting apparatus at said outlying station for initiating calls, a plurality of receivers at said central receiving station arranged in a predetermined sequence,

means for invariably assigning incoming callsto the lowest numbered idle receiver, and means whereby any one of said receivers may be rendered non-operative to receive any incoming signals.

73. In a telegraphic switching system, a switchboard having a number of telegraphic call receiving sets arranged in a predetermined sequence, in combination with means including circuit connections whereby an incoming telegraphic call will be switched to the lowest numbered idle telegraphic call receiving set and whereby if a still lower numbered telegraphic call receiving set becomes idle before an incoming telegraphic call is initiated said incoming telegraphic call will be switched to said still lower numbered telegraphic call receiving set.

74. In a signaling system, a central station, central telegraph apparatus, a substation, substation telegraph apparatus, a line connecting said stations, a relay at said central station controlling the connection of said telegraph apparatus into operative relation, switching apparatus at said central station for selecting the central telegraph apparatus in response to a calling operation performed at the substation, and a circuit arrangement wherein said relay which sets the selected apparatus at the central station into operation is energized throughout the call, the energizing circuit being broken by the apparatus at the central station on completion of the call.

'15. In a signaling system, a substation, a sea tral station, a connecting relay at said central station operated in the action of said substation calling said central station, a holding circuit for said relay, and means solely operable at the sentral station for releasing said relay.

76. In a telegraph system, a first station, a sec==- nd station, a line circuit connecting said stations, a motor at said second station, a receiver and transmitter at said second station, and transmitter being operable to send telegraphic signals by opening said line circuit in code man' ner, and means for starting and stopping said motor, said means being operative also to render said transmitter incapable of opening said line when in condition to stop said motor.

77. In a telegraph system, a telegraph receiver, a telegraph transmitter, a motor for driving said receiver and transmitter, control mechanism for stopping and starting said motor, and an electrical contact in said control mechanism for disabling said transmitter.

78. In a telegraph system, a telegraph receiver, a motor for driving said receiver, electrical signal transmitting contacts, control mechanism for starting and stopping said motor, and an electrical contact in said control mechanism for shortcircuiting said transmitting contacts.

'79. In a telegraph system, a telegraph receiver, a motor for driving said receiver,. a line circuit, electrical signal transmitting contacts for opening and closing said line circuit in code manner, control mechanism for starting and stopping said motor and an electrical contact in said control mechanism for short-circuiting said transmitting contacts.

acce ts 80. In a telegraph system, a first station, a second station, a line connecting said stations, a receiver and transmitter at said second station, a motor at said second station for driving said receiver and transmitter, a key at said second station for opening said line circuit, and control means for starting and stopping said motor, said means being effective to render said key ineffective when said means is in condition to control said motorto run.

81. In a telegraph system, a first station, a sec-- ond station, a line circuit connecting said stations, 2. receiver and transmitter at said second station, said transmitter being adapted to transmit telegraph signals by opening said line circuit in a code manner, a motor for driving said transmitter, a key at said second station for opening said line circuit, mechanism responsive to said I key whereby in response to the opening of said line circuit by said key said motor will be started, thereby rendering said transmitter effective, and electrical contacts in said mechanism for preventing said key from opening said line circuit when said transmitter is effective to open said line circuit.

82. In a telegraph system, a first station, a remote station, a telegraph set at said remote station, a motor at said remote station for operating said set, electrical contacts normally open for maintaining said motor normally in nonoperating condition, an electromagnet at said remote station responsive to current from said first station, said magnet controlling said contacts, and further contacts controlled by said magnet for rendering said magnet unresponsive.

83. In a telegraph system, a first station, a remote station, a telegraph set at said remote station, a motor at said remote station for operating said set, electrical contacts normally open for maintaining said motor normally in non-operating condition, a line circuit connecting said first station and said remote station, an electromagnet in said line circuit at said remote station responsive to current in said line circuit from said first station, said magnet controlling said contacts, and further contacts controlled by said magnet for rendering said magnet unresponsive to currents in said line circuit.

84. In a telegraph system, a first station, a remote station, a telegraph set at said remote station, a motor at said remote station for operating said set, electrical contacts normally open for maintaining said motor normally in nonoperating condition, an electromagnet at said remote station responsive to current from said first station, said magnet controlling said contacts, further contacts controlled by said magnet for rendering said magnet unresponsive, and further means at said remote station f0r'rendering said magnet again responsive to current from said first station.

85. In a telegraph system, a central station, a remote station, a telegraph set at said remote station, a motor for operating said telegraph set, means for maintaining said motor normally in a non-operating condition, and furthermeans at said remote station controlled from said central station for starting said motor thereat into op eration and for simultaneously rendering said further means non-responsive.

86. In a printing telegraph exchange system, a plurality of customers stations, a central station, a normally unopera-ted lino clay and a normally unoperated cut-01f relay at said central station individual to each of said customers stations, a single said customers stations and said central station, means for operating both said line relay and said cut-oft relay when one of said customers stations is calling, and means for operating said outofl relay alone when one of said customers stations is being called.

8'7. In a printing telegraph exchange system, a customers station, a central station, a receiving printer, a sending printer, incoming and outgoing switches at said central station, a single line between said customers station and said central station, means for connecting said customers station over said line and through said incoming switches to said receiving printer, and means for connecting said sending printer through said outgoing switches and over said line to said customers station.

88. In a printing telegraph exchange system, a customer's station, a central station, a receiving printer at said central station, a communication circuit between said customers station and said printer, an independent release circuit for maintaining said communication circuit at said central station, and means under control of the operator of said printer for breaking said release circuit and thereby disestablishing said communication circuit.

89. In a printing telegraph exchange system, a customers station, a central station, an automatically operative switch and a cut-oil relay at said central station, a line extending from said customers station to said switch, another circuit extending from said cut-ofi relay to said switch, means for operating said switch to extend said line to said central station, a normally unioperated relay at said central station, means responsive to the operation of said switch for operating said relay and means responsive to operation or said relay for extending said other circuit to ground associated with said relay.

90. In a printing telegraph exchange system, a customers station, a central station, a cut-oi! relay, an automatic switch, a receiving printer line circuit between each oi! set and a relay at said central station, means for extending a release circuit from said cut-oil relay to said automatic switch and means for operating said switch, under control 01 said customer's station, means responsive to the operation of said switch for energizing said relay, and means responsive to the operation of said relay for extending said release circuit printer set. o

91. In a printing telegraph exchange system, a central station, a printer at said station, a closed local circuit through said printer, a customers station, automatic means for establishing connection between said customers station and said central station printer, and means responsive to said interconnection for breaking said closed local circuit through said printer.

92. In a printing telegraph exchange system, a plurality of customer stations, printing telegraph equipment and driving means therefor at each of said stations, a central station, printing telegraph equipment and driving means therefor at said central station, a single wire closed circuit between said customer stations and said central station, automatic means for interconnecting the printing telegraph equipment at said customer station and said central station, and means responsive to said interconnection for starting the driving means at said customer station.

93. A telegraph signaling system comprising a plurality of outlying stations each station being provided with telegraphic instrumentalities operated by a motor, plurality of receivers connectible with said instrumentalities over circuits, selecting means controllable from any one of said outlying stations for selecting an idle one of said receivers whenever any of said receivers is idle and establishing a connection therebetween and said instrumentalities, and means responsive to the establishment of such connection for starting the motor at the station.

EDWARD E. KLEINSCHMIDT.

to said receiving a central station comprising a 

